The only bulbs that will make a difference are those that are on all the time - the headlight, tail light, and marker lights. Turn signals take a good shot of power, but are on so rarely that they won't affect charging.
Usually we want a brighter headlight so a lower power one is undesirable. LED headlights are coming but there aren't any yet.
Marker lights can just be disconnected, saving almost 15 Watts of power (0.6A each). If you really like the markers you should get LED conversions.
The tail/stop light uses another 1157 bulb, 7W on tail and 32W on stop. You can't eliminate the tail/stop lamp obviously. The stop light is only on occasionally but it's usually on when stopped and idling with the lowest alternator output. Reducing these loads will help maintain battery charge.
For the tail/stop lamp you need a really bright bulb; that's why the 1157 takes almost as much juice as the stock headlight low beam. You want the stop light to be very noticeable even in bright sun.
I have tried many LED lamp conversion clusters and found them to be, well, a cluster #$%*. Dim, dim, dim, and dimmer - adequate at night but dangerously dim in sunlight. I have not tried the customdynamics.com 38mm cluster claimed to be the brightest cluster made.
I am using the superbrightleds.com Luxeon Star single LED 1157 replacement 1157-RLX3 in a standard Stanley large tail light unit. It is astoundingly bright, stunning at night and more than adequate in sunlight. Even with a single emitter there's enough light bounced around inside the reflector and lens to light up the license plate to an almost legal level (I think white light is required to be legal). It seems strange that one LED is brighter than an array or 30+ LEDS but it is. I'm certain this would beat the customdynamics.com guarantee challenge.
The single LED is not applicable to the marker/turn signal units - you need a right angle LED unit. I have been unable to find a conversion 90 degree LED cluster with enough light to be useful so I just disconnect the markers and use the stock filament bulbs for turn signals. They take 50W or so when flashed ON but as mentioned that load is very infrequent. You can get complete LED marker/signal units and mount them somehow; making a complete assembly with adequate light is MUCH easier than making a conversion lamp to work with the stock lens and reflector.
Using LED turn signals will disable the stock flsher, it needs the higher load current from filament lamps. Adding "compensators" defeats the power saving of LED lamps - they are load resistors that draw the power a normal lamp would and just heat up. Just install a 3 wire electronic flasher and the LED signals will work with very little extra power draw. (The 3-wire flasher uses a bit of power to operate whereas the 2-terminal stock flasher uses the lamp power without any extra load)
